Amino acids are the building blocks of proteins. They band together in chains to form the stuff from which your life is born. Think of amino acids as Legos for your life.

It’s a two-step process: Amino acids get together and form peptides or polypeptides. It is from these groupings that proteins are made. And there’s not just one kind of amino acid.

A total of 20 different kinds of amino acids form proteins. The kinds of amino acids determine the shape of the proteins formed. Commonly recognized amino acids include glutamine, glycine, phenylalanine, tryptophan, and valine. Three of those — phenylalanine, tryptophan, and valine — are essential amino acids for humans; the others are isoleucine, leucine, lysine, methionine, and threonine. The essential amino acids cannot be synthesized by the body; instead, they must be ingested through food.

One of the best-known essential amino acids is tryptophan, which performs several critical functions for people. Tryptophan helps induce normal sleep; helps reduce anxiety, depression, and artery spasm risk; and helps produce a stronger immune system. Tryptophan is perhaps most well-known for its role in producing serotonin, which is what gets all the press at Thanksgiving time for putting you to sleep after the big holiday feast.